My 2000 GLX used to have a CEL issue that was quite annoying.
Before I had the bread to get it fixed, I would just unhook the battery positive side, wait 20 seconds or so and reconnect. It would erase the CEL code and everything would be fine until a few weeks later it would come on again.
With my 1.8t (maybe others too?) the turbo would not work once the CEL was on, it would disable itself (spelled crappy to drive) Once I reset it as listed above, it would be a rocket again.
Once I finally took it in, the mechanic sctatched his head as he noticed all the disconnects in the VAG COM record..
I never had any trouble with the radio either, the code came on a card that I kept in the owners manual. But I never ever had to punch it in. The radio would be just fine after restart.
Go change your battery and relax.